The Enigma Collection


The Enigma Collection is meant to be a Web portal for information about the German cipher machine Enigma in all it variations. In the beginning this Web page should be seen as a kind of note board where I post information when my time and energy allows me to do so. Later on, the page hopefully will take on a more definitive form and perhaps it will even be more pleasing to the eye. For the time being the most important issue is to have a place where I can publish my Enigma notes. At the moment I am working on a detailed history of the Enigma and when this will be published, hopefully next year, I plan to publish here many of my research notes and other documents.


Enigma Publications

Here are some of our Enigma related publications from Cryptologia:

Historical Documents

Here are some more historically oriented papers.

Graham Ellsbury has published an impressive collection of historical and cryptanalytical reports. Here is a selection from his
The Enigma and the Bombe page:

Cryptanalytical Documents

For the students who want to fully understand how to analyse and break the Enigma a close study of Alan Turing’s Treatise on Enigma is highly recommended. The papers written by C.H.O’D. Alexander, The Alexander Papers, also contain many important techniques on how to cryptanalyse the Enigma.

The Polish break into the Enigma is described by Marian Rejewski in his paper on  Breaking the Enigma Cipher  The paper has been transcribed by Enrico Grigolon and is reproduced here with the permission of The Institute of Mathematics ©, The Polish Academy of Sciences.

Professor Jiří Tůma has prepared a presentation on the use of permutation group for breaking the Enigma:
Permutation Groups and the Solution of German Enigma Cipher

A question that is frequently posed is how to recover the wheel (rotor) wiring of a machine like the Enigma. Alan Turing explains in his Treatise on Enigma the ‘Rodding’ and ‘Buttoning-up’ procedures that can be used for wiring recovery. Frank Carter has written two very good articles that explain the principles behind ‘Rodding’ and ‘Buttoning-up’, two techniques developed by Dillwyn Knox. They are available here together with other cryptanalytical articles written by Frank Carter. Previously these article where available from the The Bletchley Park Web pages, but now all cryptanalytical information seems to have vanished. I am therefore hosting local copies here:

To further increase the knowledge about this topic I am releasing two documents that explain in more detail how to recover the wheel wiring. The first document is written by Dr. Rudolf Kochendörffer (21.11.1911 – 23.8.1980), a German mathematician and Professor at the University of Dortmund who specialized in algebra and group theory. The paper is not dated and as it is in English it probably has been translated by the British or Americans after the Second World War. The text deals with the commercial Enigma, Enigma K. My first guess was that it was written in the early 1930s, but since then I have learned that in 1944 he was an Uffz. (Unteroffizier – non-commissioned officer) working in the Mathematische Referat (mathematical department) of OKH / In 7/IV the German Army High Command’s cryptographic organization. The second document is written by Lt. Robert E. Greenwood, Lt. Andrew M. Gleason, Lt. Alfred H. Clifford and Lt. Cdr. E. H. Hanson, all officers in the US Navy and attached to its signal intelligence department OP-20-G. The wiring recovery method that is described is a lot more powerful than the ‘Rodding’ and ‘Buttoning-up’ methods described by Alan Turing, mainly because it allows recovery of the wiring even when the Stecker is unknown.

The Enigma Series

This series consists of original memoranda written by members of the cryptanalytical research section of the U.S. Naval Communications Intelligence Staff, OP-20-G, and by others working with this research group, OP-20-GE – previously OP-20-GM, whose section head was Lt. Commander Howard H. Campaigne.

I should like to thank Ralph Erskine and Philip Marks for their help with these reports. Ralph Erskine did the first archive research in the Crane Collection located in Record Group 38 at NARA, College Park and he made the first set of copies. Philip Marks then revisited the collection on several occasions to make copies of the reports that I was missing.

The Series Foreword gives the ground rules for understanding these publications.

The Enigma Series Index.

Decoding Projects

Patents and Manuals

Arthur O. Bauer has published a large number of German, Dutch, French, English and US Enigma patents. He has also published a copy of the German instruction manual for the Naval Enigma M4. The copies are available here:

General Information

Enigma Messages and Keys

Enigma Papers and Thesis

Enigma Simulators

Replica Machines

Enigma Links

Here are a few links to other sources of Enigma information:


All rights to the material described on these pages belong to
Frode Weierud, © February 2016

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